/Engine/Plugins/Online/OnlineServices/Source/OnlineServicesInterface/Public/Online/Sessions.h
This event will trigger as a result of joining a session.
[TOnlineEvent](API\Plugins\OnlineServicesInterface\Online\TOnlineEvent)< void(const [FSessionJoined](API\Plugins\OnlineServicesInterface\Online\FSessionJoined) &)> OnSessionJoined()